libsimple_support/unit_tests/meta_find.cpp

#include "simple/support/meta/find.hpp"
#include "simple/support/meta/bind.hpp"
#include "simple/support/meta/list.hpp"

#include <type_traits>

using namespace simple::support;


template <size_t i>
using size_constant = std::integral_constant<size_t, i>;

// find double counting floats on the way
template <typename count, typename T>
struct count_float_until_double
{
	static constexpr bool value = std::is_same_v<T, double>;
	using binding = size_constant<count{} + std::is_same_v<T,float>>;
};

// find double counting floats on the way
template <typename T, typename count>
struct count_float_until_double2
{
	static constexpr bool value = std::is_same_v<T, double>;
	using binding = size_constant<count{} + std::is_same_v<T,float>>;
};

int main()
{
	static_assert(meta::find_v<bool,
		meta::list<char, int, bool, double>>
		== 2
	);

	static_assert(meta::find_v<short,
		meta::list<char, int, bool, double>>
		== 4
	);

	static_assert(meta::find_if_v<std::is_floating_point,
		meta::list<char, int, bool, double>>
		== 3
	);

	static_assert(meta::find_if_v<std::is_array,
		meta::list<char, int, bool, double>>
		== 4
	);

	static_assert(std::is_same_v<
		meta::find_if_t<std::is_floating_point,
			meta::list<char, bool, double, int>>,
		double
	>);

	using found = meta::find_t
	<
		meta::bind<count_float_until_double, size_constant<0>>,
		meta::list<char, float, bool, float, double, int, float>
	>;

	// found double
	static_assert(std::is_same_v<found::type, double>);
	// at index 4
	static_assert(found::value == 4);
	// counted 2 floats
	static_assert(found::functor::binding{} == 2);

	using found2 = meta::find_t
	<
		meta::bind_after<count_float_until_double2, size_constant<0>>,
		meta::list<char, float, bool, float, double, int, float>
	>;

	// found double
	static_assert(std::is_same_v<found2::type, double>);
	// at index 4
	static_assert(found2::value == 4);
	// counted 2 floats
	static_assert(found2::functor::binding{} == 2);

	return 0;
}